My D80v2 with SST40 has a similar distinct blue/violet ring around the periphery of the beam. It’s noticeable but in no way affects the usefulness of the light. It resides outside the useful area of the beam and isn’t a problem in actual use.
In practice, it doesn’t really affect tint/CRI since it lands far outside the usable light pattern.
For what it’s worth, I have an S2+ with a 219c which does not have any visible blue artifacts around the beam.
I guess we don’t see it mentioned because it doesn’t really affect the performance of the light. If it was right around the hotspot we’d probably see many people complaining about it. It’s far enough out that it’s easy to just ignore it.
If it really bothers you, perhaps you could try a different reflector/optic or perhaps a non-AR coated glass window. If that doesn’t help, consider a different emitter.
Its because the reflector shape is not perfectly optimized for the LED. If you want a clean hotspot you need to use TIR lens. But it will be less bright.
I’m pretty sure reviewers don’t mention it because it doesn’t effect the usability of the light like tint, CRI or PWM may. Nobody uses the uses the area outside of the useful spill of a light to do anything. At any rate, the halo is from a combination of AR glass and the bezel of the light.
Blue Convoy S2, No AR glass. Deep blue halo like yours. Green halo from very thick GITD Oring.
Green S2+, AR Glass, TIR (Triple). Green halo
Purple S2+, AR Glass. Huge purple halo
Black S2+, No AR glass. No halo
Desert Tan S2+, AR glass. Brownish-orange halo, pretty faint.
Interesting thanks for the pics … as someone said above the s2+ seems quite susceptible to these issues, you might get the same color halo as yr light !!!
Interesting that the BLF A6 with AR which is probably the most similar light in price, form and function doesnt have the halo in practical use, though you can see a bit of color with the same type of shot as above. Seems like the blackbezel helps
Compare to s2+ SST40
As to if it “matters” … well thats up to the end user perhaps not flashaholics who go off about a slightly off tint or slightly low CRI
BLF A6, roughly half beam shot, so well within the field of direct view… just fine
Same shot SST40 … well look at that purple ring right in the field of vision
Methinks that the average user or muggle if one wants to feel better, would notice that first before any small tint or CRI differences
But then it doesnt seem important for reviewers to even say a quick word or two about it …
I agree. The angle of the S2+ bezel (though as seen above, the S2 does it as well) reflects a ring of light that gets coloured by the anodizing, and also picks up whatever colour the AR glass tends to throw off at extreme angles.
Funny you mention that particular model because I’ve seen about half a dozen of these at work and their owners don’t really seem to mind. To me, the worst thing about those is the horrendously blue emitter. But I digress; different strokes I suppose.
Maybe try one of those drop-in TIR optics for the S2 and see if it cleans up the beam.
Fun fact, the BLF D80v2 casts a red halo, then a bright turquoise halo inside, and then proceeds to cast the entire god damn rainbow as a halo before it gets to the beam.
It’s funny how these Halo/Saturn rings are just being discussed these days—this has been an issue for me for years —- some lights are very noticable—others not so much —- I have 100s of lights and out of all of those I might have 25 or so without any sort of ring—-the bigger the light—the bigger the ring—-one of the most aggravating to me is the multiple rings 3-4-5 of them —— If I really like the light and it has this issue I just DC Fix it